This invention relates to thermoplastic materials having a satisfactory strength at elevated temperatures, and their use in the manufacture of molded articles, especially panels or sheets.
It is known to utilize thermoplastic materials, for example in the form of panels or sheets, to make moisture seals. Such panels or sheets can be joined together to form rather large sealed surfaces either by heat welding or by the use of a solution welding agent such as a swelling agent or a special adhesive. Alternatively, they can also be loosely laid on substrates such as concrete, wood, bitumen, and thermal insulating materials containing entrapped air; or can be glued to such supporting materials at a few selected locations or over their entire surface area with the use of special large-surface area adhesives.
Important properties of the thermoplastic materials include suitable rheological characteristics, satisfactory weldability, and good resistance to weathering and other environmental influences. Of especially great significance for the panels or sheets produced from these materials are the mechanical characteristics of the latter. Particularly, sufficient strength characteristics are necessary so that the panels or sheets can withstand long-term tensile or expansion stresses at elevated temperatures, e.g., up to 70.degree. C., such as occur on flat roofs during the height of the summer in Central Europe or in countries having a tropical or subtropical climate.